1. Field of the Invention
The present invention relates to a method of impregnating fibrous material with a resin which is used as a matrix or binder in the production of a composite having application as a winding in the manufacture of hollow articles such as cylinders and spheres, for example, rocket motor cases, for confining fluid medium under high pressure.
2 Description of the Prior Art
In the prior art manufacture of composites of the above-mentioned character, continuous cloth, roving or tow usually is passed through a dip tank of the resin that is to be used as a matrix. This procedure is common to filament winding, prepregging and pultrusion operations. With these systems, control of the resin percent by weight is through wipe or orifice scrape of excess resin from the fibrous material. Solvent extraction is used in conjunction with the wipe or scrape by prepreggers. With a prepreg operation, the resin content is often held to .+-.3% by weight, but presents problems in long run lots due to the evaporation of the solvent in the dip tank mixture. With a polar filament winding operation, historically, it has not been possible for the tumbling winding arm to house a dip tank system, and processing was limited to either prepreg or a hand brushed on coating of resin.
The following U.S. patents are a representative sample of the prior art methods of and apparatus for conditioning and handling the fibrous materials preliminary to its application as a winding in the manufacture of hollow articles: Daley et al U.S. Pat. No. 2,792,324; Schneiderman et al U.S. Pat. No. 3,021,241; and Young U.S. Pat. No. 3,047,191. Limitations of the known prior art systems of impregnation are: (1) scrape abrading of fibers; (2) inaccurate control of resin content; and (3) gravity dependency.